PRISTIQ
Clinical safety rating: caution
Comprehensive clinical and safety monograph for PRISTIQ (PRISTIQ).
Desvenlafaxine is a serotonin-norepinephrine reuptake inhibitor (SNRI). It binds to the serotonin transporter (SERT) and norepinephrine transporter (NET), inhibiting reuptake of serotonin and norepinephrine, thereby increasing their synaptic concentrations.
| Metabolism | Primarily metabolized via conjugation (glucuronidation) and to a minor extent via CYP3A4. Desvenlafaxine is not a substrate for CYP2D6 or CYP1A2. |
| Excretion | Renal: 87% (45% desvenlafaxine unchanged, 42% as metabolites); biliary/fecal: minimal (<1%) |
| Half-life | Desvenlafaxine: ~11 hours (range 8-15 h); supports once-daily dosing |
| Protein binding | Low: ~30% bound to plasma proteins (primarily albumin) |
| Volume of Distribution | ~3.4 L/kg (large, indicating extensive tissue distribution) |
| Bioavailability | Oral: ~80% (desvenilafaxine succinate monohydrate) |
| Onset of Action | Oral: therapeutic benefit may be observed within 1-2 weeks, but full effect typically requires 4-8 weeks |
| Duration of Action | ~24 hours; once-daily dosing due to long half-life and sustained-release formulation |
50 mg orally once daily, with or without food; may increase by 50 mg every 7 days to a maximum of 100 mg once daily; maximum dose is 100 mg/day (some studies up to 400 mg/day but not recommended).
| Dosage form | TABLET, EXTENDED RELEASE |
| Renal impairment | GFR 30-89 mL/min: maximum 50 mg once daily; GFR 15-29 mL/min: 50 mg every other day; GFR <15 mL/min or on dialysis: 50 mg every other day (dialysis not effective in removing drug). |
| Liver impairment | Child-Pugh Class A: usual dose; Class B: 50 mg once daily, maximum 50 mg/day; Class C: 50 mg every other day, maximum 50 mg/day. |
| Pediatric use | Not approved for pediatric use; safety and efficacy not established. |
| Geriatric use | No specific dose adjustment other than renal function; start at 50 mg once daily; elderly may have increased sensitivity; monitor for hyponatremia and orthostatic hypotension. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for PRISTIQ (PRISTIQ).
| Breastfeeding | Desvenlafaxine is excreted in human breast milk with an M/P ratio of approximately 0.4. Infant doses are estimated at about 5-8% of maternal weight-adjusted dose. Monitor infant for signs of sedation, poor feeding, and weight gain. Weigh benefits of breastfeeding against potential risks. |
| Teratogenic Risk | First trimester: Limited human data; animal studies show no evidence of teratogenicity at clinically relevant doses, but some studies show delayed ossification at high doses. Second and third trimesters: Risk of persistent pulmonary hypertension of the newborn (PPHN) and neonatal adaptation syndrome (irritability, feeding difficulties, respiratory distress) with late third trimester exposure. |
■ FDA Black Box Warning
Suicidality and Antidepressant Drugs: Increased risk of suicidal thinking and behavior in children, adolescents, and young adults taking antidepressants. Monitor for clinical worsening and emergence of suicidality. Not approved for use in pediatric patients.
| Serious Effects |
["Hypersensitivity to desvenlafaxine or any component","Concurrent use with MAOIs or within 14 days of MAOI discontinuation","Uncontrolled narrow-angle glaucoma"]
| Precautions | ["Serotonin syndrome or neuroleptic malignant syndrome-like reactions","Elevated blood pressure (dose-dependent)","Increased risk of bleeding (especially with NSAIDs or anticoagulants)","Mydriasis (use cautiously in patients with elevated intraocular pressure)","Activation of mania/hypomania","Seizure risk","Discontinuation syndrome (taper dose)","Sexual dysfunction","Syndrome of inappropriate antidiuretic hormone secretion (SIADH)","Angle-closure glaucoma (monitor narrow-angle patients)"] |
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| Fetal Monitoring | Monitor maternal blood pressure and heart rate regularly due to risk of hypertension and tachycardia. Assess for signs of serotonin syndrome, especially with concurrent use of other serotonergic drugs. Fetal monitoring: consider serial growth ultrasounds in third trimester due to association with low birth weight; monitor for neonatal adaptation syndrome after delivery. |
| Fertility Effects | Animal studies show no significant impact on fertility at clinically relevant doses. Human data are limited; no definitive evidence of adverse effects on fertility. |